The specific objective of this clinical investigation is to determine how selected nursing intervention of endotracheal tube suctioning (ETTS), manual hyperventilation (MH), passive position changes, and hygiene measures, when administered to normothermic severe closed head injured persons grouped according to age, admission BAC and resting mean intracranial pressure, will alter significantly their cerebrovascular status as measured by change in mean arterial blood pressure (MABP), mean intracranial pressure (MICP), cerebral perfusion pressure (CPP), heart rate (HR) and end tidal carbon dioxide (ETCO2). The selected nursing interventions chosen for study incorporates the most important nursing care measures likely to be used in the care of the severe closed head injured person. It is believed that when these nursing interventions are administered effectively to head injured persons, pulmonary complications, (i.e. pneumonia and atelectasis), pressure necrosis, skin irritation and breakdown can be prevented. Thus, by establishing the safe limits of nursing interventions, patient morbidity can be reduced and nursing care of these severe head injured persons can become more cost effective. The independent variable will be selected nursing interventions, age, admission blood alcohol concentration (BAC) and resting MICP, while dependent variables will be changes in MABP, MICP, CPP, HR and ETCO2 as reflecting changes in cerebrovascular status. A partial between-subject and partially within-subject (repeated measures) design will be used. A four-way analysis of variance (ANOVA) will be used to assess the influence of the independent variables on the dependent variables. The dependent variables will be analyzed separately. The independent variables in the between subjects portion of the ANOVA are age, blood alcohol concentration, and mean intracranial pressure. The independent variable of the within subjects portion of the ANOVA is the time of measurements. Trend analysis will be performed to answer whether the effects of the interventions including recovery period, differ depending upon previous interactions. Upon completion of the experiments, if the number of observations in the cells formed by the independent variables are unbalanced, a multiple regression analysis will be employed as a robust statistical alternative.